Lubricant additive and lubricant composition

ABSTRACT

A lubricating oil additive contains at least one steroid derivative selected from steroid saturated fatty acid ester, steroid carbonate ester and steroid ether. A lubricating oil composition added with the lubricating oil additive exhibits a low friction coefficient and excellent wear resistance, heat resistance and oxidation resistance stability.

TECHNICAL FIELD

The present invention relates to a lubricating oil additive andlubricating oil composition.

BACKGROUND ART

As the reduction in emission of carbon dioxide is being demanded inperspective of the global environment, more efficient utilization ofenergy is getting increasing attentions. For instance, machinesincluding sliding portions can efficiently utilize the energy byreducing the friction energy with use of lubricating oil. In addition,prevention of wear, which is also one of the most important functions ofthe lubricating oil, leads to increase in lifetime of machines. Further,in perspective of waste reduction, the lubricating oil is demanded tohave more long-drain capabilities, and to exhibit high oxidationstability and heat resistance.

As additives capable of friction reduction, a sulfur-containingmolybdenum composition such as molybdenum dithiocarbamate (MoDTC) hasbeen in use (see e.g., Patent Document 1).

Patent Document 1: JP-A-07-145187

DISCLOSURE OF THE INVENTION Problems to Be Solved by the Invention

However, the metal-containing compounds disclosed in Patent Document 1may be harmful to exhaust-purifying catalysts, so that ashlesslubricating oil additives are being desired. Further, though sulfur andphosphorus are also capable of preventing wear, reduction of the use ofthem are demanded in view of their toxicity and harm to theexhaust-purifying catalysts.

Hence, an object of the invention is to provide a so-called ashlesslubricating oil additive capable of providing sufficient lubricationwithout use of metals (e.g., Mo), sulfur or phosphorus, and to provide alubricating oil composition added with the lubricating oil additive.

Means for Solving the Problems

In order to solve the above-described problems, aspects of the inventionprovide the following lubricating oil additives and lubricating oilcompositions:

[1] a lubricating oil additive, containing at least one lanolin alcoholderivative selected from the group consisting of lanolin-alcoholsaturated fatty acid ester, lanolin alcohol carbonate ester and lanolinalcohol ether;[2] a lubricating oil additive, comprising at least one steroidderivative selected from steroid saturated fatty acid ester, steroidcarbonate ester and steroid ether;[3] the lubricating oil additive according to [2], in which the steroidderivative is a cholesterol derivative;[4] a lubricating oil composition, containing: lubricating base oil; andthe lubricating oil additive according to any one of [1] to [3];[5] the lubricating oil composition according to [4], further containingat least one additive selected from the group consisting of viscosityindex improvers, pour point depressants, antioxidants, ashlessdispersants, friction modifiers, metal detergents, antiwear agents, rustinhibitors, metal deactivators, anti-emulsifiers and antifoaming agents;and[6] the lubricating oil composition according to [4] or [5], in whichthe lubricating oil composition is used for engines, gears orindustries.

The lubricating oil additive provided according to the aspect of theinvention, although not containing a metal (e.g., Mo), sulfur orphosphorus, is capable of providing sufficient lubrication.Specifically, the lubricating oil composition obtained by adding thelubricating oil additive to suitable base oil exhibits a low frictioncoefficient and excellent wear resistance.

BEST MODE FOR CARRYING OUT THE INVENTION

The lubricating oil additive according to the aspect of the inventioncontains at least one lanolin alcohol derivative selected fromlanolin-alcohol saturated fatty acid ester, lanolin alcohol carbonateester and lanolin alcohol ether.

The lanolin alcohol means a neutral alcohol component obtained bysaponifying lanolin. Lanolin is a light-yellow waxen substance obtainedby refining “wool grease” (i.e., collected wash with which wool has beenwashed) through deacidification, decoloration and deodorization.

Lanolin alcohol contains: a steroid skeleton such as cholesterol,desmosterol, lanosterol, dihydrolanosterol and lanosterol; and abranched chain alcohol having 16 to 28 carbon atoms.

Such lanolin alcohol is available at Nippon Fine Chemical Co., Ltd. Byesterifying lanolin alcohol and fatty acid chloride under the presenceof a base, lanolin alcohol fatty acid ester is obtainable.

Alternatively, lanolin alcohol fatty acid ester is also obtainable byreacting lanolin alcohol and saturated fatty acid with each other underthe presence of a dehydration-condensation agent such as DCC(dicyclohexylcarbodiimide), DIC (diisopropylcarbodiimide) and EDC(1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride).

Further alternatively, lanolin alcohol fatty acid ester is alsoobtainable by dehydrating a sterol compound and saturated fatty acidunder the presence of an acid catalyst.

Lanolin alcohol carbonate ester is obtainable by reacting lanolinalcohol and chlorocarbonate ester with each other under the presence ofa base.

Lanolin alcohol alkyl ether is obtainable by reacting lanolin alcoholand alkyl bromide with each other under the presence of a base.Alternatively, lanolin alcohol alkyl ether is also obtainable bydehydrating and condensing lanolin alcohol and chain alcohol under thepresence of an acid.

The lubricating oil additive according to the aspect of the inventioncontains at least one steroid derivative selected from steroid saturatedfatty acid ester, steroid carbonate ester and steroid ether.

The steroid is a generic term for referring to compounds havingcyclopenta[a]phenanthrene skeletons, of which structures are exemplarilyrepresented by the following formulae (1) to (5).

The steroid saturated fatty acid ester, steroid carbonate ester andsteroid ether are compounds in which one or more saturated fatty acidester group, carbonate ester group and ether group are bonded to theabove-described skeletons.

Examples of the steroid saturated fatty acid ester are cholesterolsaturated fatty acid ester and cholestanol saturated fatty acid esterrespectively represented by the following formulae (6) and (7).

In the above formulae (6) and (7), R¹ and R² represent a branched ornon-branched saturated hydrocarbon group. When R¹ and R² are ofunsaturated structure, the obtained lubricating oil additive may exhibitlower wear resistance and deteriorated oxidation stability. In addition,R¹ and R² preferably have 1 to 30 carbon atoms, more preferably 9 to 24carbon atoms. When R¹ and R² have more than 30 carbon atoms,availability may be deteriorated. Examples of carboxylic acids forproviding esters having R¹ and R² as their basic skeletons are apelargonic acid, capric acid, lauric acid, myristic acid, pentadecanoicacid, palmitic acid, margaric acid, stearic acid, nonadecane acid,eicosanoic acid, docosanoic acid and tetra docosanoic acid.

Further, the lubricating oil additive is preferably a cholesterolsaturated fatty acid ester represented by the formula (6) in view of theavailability and friction reduction capabilities.

Such steroid saturated fatty acid ester is readily available as amarketed product (for instance, cholesterol stearate by Wako PureChemical Industries, Ltd.). Alternatively, by esterifying a sterolcompound and saturated fatty acid chloride under the presence of a base,sterol saturated fatty acid ester is obtainable. Further alternatively,sterol ester is obtainable by reacting a sterol compound and saturatedfatty acid with each other under the presence of adehydration-condensation agent such as DCC (dicyclohexylcarbodiimide),DIC (diisopropylcarbodiimide) and EDC(1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride). Stillfurther alternatively, sterol ester is also obtainable by dehydrating asterol compound and saturated fatty acid under the presence of an acidcatalyst.

Examples of the steroid carbonate ester are cholesterol carbonate esterand cholestanol carbonate ester respectively represented by thefollowing formulae (8) and (9).

R³ and R⁴ represent a branched or non-branched hydrocarbon group. R³ andR⁴ preferably have 1 to 30 carbon atoms, more preferably 9 to 24 carbonatoms. When R³ and R⁴ have more than 30 carbon atoms, availability maybe deteriorated. Examples of carboxylic acids for providing estershaving R³ and R⁴ as their basic skeletons are a pelargonic acid, capricacid, lauric acid, myristic acid, pentadecanoic acid, palmitic acid,margaric acid, stearic acid, oleic acid, linolic acid, linolenic acid,arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid and erucicacid.

The lubricating oil additive is preferably a cholesterol carbonate esterrepresented by the formula (8) in view of the availability.

Such steroid carbonate ester is also readily available as a marketedproduct (for instance, cholesterol oleyl carbonate by Tokyo ChemicalIndustry Co., Ltd.). Alternatively, steroid carbonate ester is alsoobtainable by reacting a sterol compound and chloroformate with eachother under the presence of a base.

Examples of the steroid ether are cholesterol ether and cholestanolether respectively represented by the following formulae (10) and (11).

R⁵ and R⁶ represent a branched or non-branched hydrocarbon group. Inaddition, R⁵ and R⁶ preferably have 1 to 30 carbon atoms, morepreferably 9 to 24 carbon atoms. When R⁵ and R⁶ have more than 30 carbonatoms, availability may be deteriorated. Examples of R⁵ and R⁶ are anonyl group, decyl group, undecyl group, dodecyl group, tridecyl group,tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group,octadecyl group, nonadecyl group and eicosyl group.

The lubricating oil additive is preferably a cholesterol etherrepresented by the formula (10) in view of the availability.

Such steroid ether is obtainable by, for instance, reacting a sterolcompound and alkyl bromide with each other under the presence of a base.Alternatively, steroid ether is also obtainable by reacting a sterolcompound and alcohol under the presence of an acid catalyst.

The lubricating oil composition according to the aspect of the inventioncontains a lubricating base oil and the above-described lubricating oiladditive. As the lubricating base oil, mineral oil and/or synthetic oilis used. The mineral oil or synthetic oil is not particularly limited,but may be suitably selected from any mineral oil and synthetic oil thathave been conventionally used as base oil of the lubricating oil.

Examples of the mineral oil are mineral oil refined by processinglubricating oil fractions by at least one of solvent-deasphalting,solvent-extracting, hydrocracking, solvent-dewaxing, catalytic-dewaxingand hydrorefining (the lubricating oil fractions are obtained byvacuum-distilling atmospheric residual oil obtained by atmosphericallydistilling crude oil such as paraffin crude oil, naphthene crude oil andaromatic crude oil) and mineral oil manufactured by isomerizing wax andGTL WAX. Namely, the examples are spindle oil, 70 neutral oil, 100neutral oil, 150 neutral oil, 500 neutral oil and bright stock.

On the other hand, examples of the synthetic oil are polybutene,polyolefin α-olefin homopolymer or copolymer such as ethylene-α-olefincopolymer), various esters (such as polyol ester, diacid ester andphosphoric ester), various ethers (such as polyphenylether), polyglycol,alkylbenzene and alkyl naphthalene. Among the above synthetic oil,poly-α-olefin copolymer is particularly preferable in view of its lowfriction coefficient. The poly-α-olefin copolymer preferably has amolecular weight of 250 to 5000, more preferably 300 to 3000. When themolecular weight is less than 250, oil-film breakdown is more likely tobe invited due to the low viscosity of the oil, and thus wear resistanceis unfavorably deteriorated. On the other hand, when the molecularweight is more than 5000, the viscosity is increased, and the frictioncoefficient is unfavorably increased due to increase of stirringresistance.

In the aspect of the invention, one of the above mineral oil andsynthetic oil may be singularly used or a combination of two or morethereof may be used as the base oil.

In terms of the viscosity of the base oil, kinematic viscosity at 40degrees C. is preferably 2 to 2000 mm²/s, more preferably 10 to 1500mm²/s. When the kinematic viscosity at 40 degrees C. is less than 2mm²/s, oil-film breakdown is unfavorably likely to be invited. On theother hand, when the kinematic viscosity at 40 degrees C. is more than2000 mm²/s, flow resistance is increased, and the friction coefficientis unfavorably increased.

A content of the above-described lubricating oil additive is 0.01 to 5mass % of the total amount of the composition, preferably 0.1 to 2 mass%. When the content of the lubricating oil additive is less than 0.01mass %, the friction coefficient may not be sufficiently reduced, andwear resistance may not be sufficiently enhanced. On the other hand,when the content of the lubricating oil additive is more than 5 mass %,no advantage comparable to the increased content is obtained.

As described above, the lubricating oil composition according to theaspect of the invention contains: the lubricating base oil; and thelubricating oil additive containing at least one steroid derivativeselected from steroid saturated fatty acid ester, steroid carbonateester and steroid ether. The lubricating oil composition can exhibit alow friction coefficient and excellent wear resistance without use ofmetals (e.g., Mo), sulfur or phosphorus.

In addition, the above-described steroid derivative is a so-calledashless compound containing none of metal, sulfur or phosphorus. Thus,when used in internal combustion engines, the steroid derivative cansuppress the degradation of catalysts and pose less environmental load.

Accordingly, the lubricating oil composition according to the aspect ofthe invention is favorably usable in machines in which friction wear isto occur. For instance, in the form of engine lubricating oil, thelubricating oil composition is favorably usable in gasoline or dieselinternal combustion engine for vehicles and ships. Further, in the formof gear lubricating oil, the lubricating oil composition is favorablyusable in differential gears, mission gears, manual transmissions,automatic transmissions and continuously variable transmissions. Stillfurther, in the form of industrial lubricating oil, the lubricating oilcomposition is favorably usable in compressor oil, cutting oil andplastic working oil. Examples of the compressor are refrigerators andvacuum pumps. The cutting oil is used in, for instance, cutting work.The plastic working oil is used in rolling work, extrusion work,pultrusion work, shear work, bending work, deep drawing work and forgework.

The lubricating oil composition according to the aspect of the inventionmay further contain suitable additives. Specifically, examples of suchadditives are viscosity index improvers, pour point depressants,antioxidants, ashless dispersants, friction modifiers, metal detergents,antiwear agents, rust inhibitors, metal deactivators, anti-emulsifiersand antifoaming agents.

Examples of the viscosity index improver are non-dispersedpolymethacrylate, dispersed polymethacrylate, an olefin copolymer (suchas an ethylene-propylene copolymer), a dispersed olefin copolymer and astyrene copolymer (such as a styrene-diene hydrated copolymer). Theweight-average molecular weight of the viscosity index improver ispreferably 5000 to 1000000, more preferably 100000 to 800000, when, forinstance, dispersed or non-dispersed polymethacrylate is used. When anolefin copolymer is used, the weight-average molecular weight ispreferably 800 to 300000, more preferably 10000 to 200000. For use inthe lubricating oil composition, one of the above viscosity indeximprovers may be singularly adopted or a plurality thereof may beadopted in combination. Typically, the content of the viscosity indeximprover is in a range of 0.1 to 20 mass % of the total amount of thelubricating oil composition.

Examples of the pour point depressant are an ethylene-vinyl acetatecopolymer, condensation product of chlorinated paraffin and naphthalene,condensation product of chlorinated paraffin and phenol,polymethacrylate and polyalkyl styrene. In particular, polymethacrylateis preferable. The content of the pour point depressant is typically ina range of 0.01 to 5 mass % of the total amount of the lubricating oilcomposition.

Examples of the antioxidant are amine antioxidants such as alkylateddiphenylamine, phenyl-α-naphthylamine and alkylatedphenyl-α-naphthylamine, phenol antioxidants such as2,6-di-t-butylphenol, 4,4′-methylenebis(2,6-di-t-butylphenol),isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate andn-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, sulfurantioxidants such as dilauryl-3,3′-thiodipropionate, phosphorousantioxidants such as phosphite, zinc dithiophosphate antioxidants andmolybdenum antioxidants. For use in the lubricating oil composition, oneof the above antioxidants may be singularly adopted, or a plurality ofthem may be adopted in combination. Typically, two or more of them arepreferably used in combination, and the content of the antioxidant ispreferably 0.01 to 5 mass % of the total amount of the lubricating oilcomposition, more preferably 0.2 to 3 mass %.

Examples of the ashless dispersant are polybutenyl succinimide,polybutenyl benzylamine and polybutenylamine that have polybutenylgroups having number average molecular weight of 900 to 3500, and theirderivatives such as their borated products. For use in the lubricatingoil composition, one of the above ashless dispersants may be singularlyadopted or a plurality thereof may be adopted in combination. Typically,the content of the ashless dispersant is in a range of 0.1 to 20 mass %of the total amount of the lubricating oil composition.

Examples of the friction modifier are an organic molybdenum compound,fatty acid, higher alcohol, fatty acid ester, oils and fats, amine,amide, phosphate ester, phosphite ester, phosphate ester amine salt,sulfur-containing compound such as olefin sulfide, sulfurized fatty acidester and dibenzyl disulfide and chloride compound such as chlorinatedparaffin. For use in the lubricating oil composition, one of the abovefriction modifiers may be singularly adopted or a plurality thereof maybe adopted in combination. Typically, the content of the frictionmodifier is in a range of 0.05 to 4 mass % of the total amount of thelubricating oil composition.

Examples of the metal detergent are sulfonate, phenate, salicylate andnaphthenate of alkali metal (e.g., sodium (Na), potassium (K)) or alkaliearth metal (e.g., calcium (Ca), magnesium (Mg)). One of the above metaldetergents may be singularly used or a plurality of them may be used incombination. The total base number and the additive amount of the metaldetergent may be suitably determined in accordance with the desiredperformances of the lubricating oil. The total base number is typically0 to 500 mg KOH/g by a perchloric acid method, preferably 20 to 400 mgKOH/g. The content is typically in a range of 0.1 to 10 mass % of thetotal amount of the lubricating oil composition.

Examples of the antiwear agent are metal dithiophosphate (e.g, Zn, Pb,Sb, Mo), metal dithiocarbamate (e.g., Zn, Pb, Sb, Mo), metal naphthenate(e.g., Pb), fatty acid metal salt (e.g., Pb), boron compound, phosphateester, phosphite ester, alkyl hydrogen phosphite, phosphate ester aminesalt, phosphate ester metal salt (e.g., Zn), disulfide, sulfurized oilsand fats, olefin sulfide, dialkyl polysulfide, diaryl alkyl polysulfide,diaryl polysulfide and solid lubricating antiwear agent such asgraphite, molybdenum disulfide, antimony sulfide andpolytetrafluoroethylene. For use in the lubricating oil composition, oneof the above antiwear agents may be singularly adopted or a pluralitythereof may be adopted in combination. Typically, the content of theantiwear agent is in a range of 0.1 to 5 mass % of the total amount ofthe lubricating oil composition.

Examples of the rust inhibitor are a fatty acid, alkenyl succinic acidhalf ester, fatty acid soap, alkyl sulfonate, polyvalent alcohol fattyacid ester, fatty acid amine, paraffin oxide and alkyl polyoxyethyleneether. The content of the rust inhibitor is typically in a range of 0.01to 3 mass % of the total amount of the lubricating oil composition.

Examples of the metal deactivator is benzotriazole, triazole derivative,benzotriazole derivative and thiadiazole derivative. The content of themetal deactivator is typically in a range of 0.01 to 3 mass % of thetotal amount of the lubricating oil composition.

As the antifoaming agent, a liquid silicone is suitable, and amethylsilicone, a fluorosilicone and a polyacrylate may be used. Thecontent of the antifoaming agent is preferably 0.0005 to 0.01 mass % ofthe total amount of the composition.

Examples of the anti-emulsifier are ethers such as polyoxyethylene alkylether and polyoxyethylene alkyl phenyl ether and esters such as sorbitanfatty acid ester, polyoxyethylene sorbitan fatty acid ester andpolyoxyethylene fatty acid ester. The content of the antifoaming agentis preferably 0.005 to 1 mass % of the total amount of the composition.

In order to better obtain the advantages of the invention, thecomposition is preferably so prepared as to contain, among the aboveadditives, the metal-containing compounds, sulfur compounds andphosphorus compounds at as small contents as possible.

EXAMPLES

Next, the invention will be described in a further detail with referenceto Examples, which by no means limit the invention.

Specifically, lubricating oil compositions as determined below wereprepared, and the lubricating properties thereof (friction coefficientsand wear resistance) were evaluated.

The components used for preparing the lubricating oil compositions areas follows.

(1) Base Oil:

(1-1) Base oil A: mineral oil of 500 neutral fraction (HG500)

(1-2) Base oil B: commercially-available oil containing antioxidants,antiwear agents and the like (general-purpose oil exemplarily used asgear oil)

(2) Additives

(2-1) FM A: cholesterol stearate (manufactured by Wako Pure ChemicalIndustries, Ltd.)

(2-2) FM B: cholesterol n-caprylate (manufactured by Tokyo ChemicalIndustry Co., Ltd.)

(2-3) FM C: cholesterol acetate (manufactured by Tokyo Chemical IndustryCo., Ltd.)

(2-4) FM D: cholesterol n-octyl carbonate (manufactured by TokyoChemical Industry Co., Ltd.)

(2-5) FM E: cholesterol isostearate (manufactured by Tokyo ChemicalIndustry Co., Ltd.)

(2-6) FM F: cholesterol oleyl carbonate (manufactured by Tokyo ChemicalIndustry Co., Ltd.)

(2-7) Molybdenum dithiocarbamate (MoDTC)

(2-8) FM G: lanolin alcohol stearate (see below)

100 g of lanolin alcohol and 40 g of pyridine were dissolved in 700 mlof toluene, and 131 g of stearoyl chloride and solution of 300-mltoluene were added at 0 degree C. The mixture was reacted for one dayand then added with water, and insoluble matters were filtrated.Subsequently, the organic layers were washed with aqueous solution of 5%hydrochloric acid and water. After being dried with magnesium sulfate,the organic layers were condensed, so that 202 g of light yellow solidwas obtained.

Examples 1 to 12 and Comparative 1

Lubricating oil compositions (sample oils) containing components shownin Table 1 were respectively prepared, which were then subjected totests detailed below for evaluation of the lubricating properties. Theresults are also shown in Table 1. For reference, the same test was alsoconducted on the base oil A (HG500) itself and the base oil B(commercially-available oil).

(1) Block-on-Ring Test

With use of a block-on-ring tester (LFW-1), the test was conducted underconditions where: the rotation speed was 500 rpm; the load was 44.5 to177.8 N (10 to 40 lbs); the oil temperature was 60 degrees C.; and thefriction time was 15 minutes.

Specifically, the amount of the sample oil was set such that the half ofthe ring was soaked therein, H-60 Test Block (manufactured by FalexCorporation) was used as the test block, and S-10 Test Ring(manufactured by Falex Corporation) was used as the test ring. Load wasapplied on the block, and the resistance caused when the ring wasrotated was measured with a strain gauge, and the friction coefficientwas obtained. In addition, width of the wear trace after the test wasalso measured.

(2) Soda Pendulum Test (JASO Method)

Soda pendulum test was conducted at the oil temperature of 60 degreesC., and the friction coefficient was obtained.

(3) Shell Four-Ball EP Test (Based on ASTM D 2783)

The test was conducted with the rotation speed of 1800 rpm at a roomtemperature, and the last non-seizure load (LNL) and last weld load(LWL) were measured, from which load wear index (LWI) was then obtained.The larger the value of the load wear index becomes, the more favorablethe load resistance capacity is.

TABLE 1 Example 1 2 3 4 5 6 7 8 Composition Base Oil A (HG500) residueresidue residue — — residue residue residue (mass %) Base Oil B¹⁾ — — —residue residue — — — Additive FM A 0.01 0.1 1 0.1 1 — — — FM B — — — —— 1 — — FM C — — — — — — 1 — FM D — — — — — — — 1 FM E — — — — — — — —FM F — — — — — — — — FM G MoDTC — — — — — — — — LFW-1 Load (N)  44.50.078 0.076 0.063 0.063 0.069 0.095 0.093 0.086 Friction  88.9 0.1180.109 0.092 0.105 0.110 0.124 0.127 0.123 Coefficient 133.3 0.136 0.1250.107 0.123 0.130 0.138 0.142 0.135 177.8 0.141 0.134 0.122 0.135 0.1380.143 0.145 0.142 LFW-1 Wear Trace Width (mm) 1.418 0.352 0.341 — —0.406 0.4922 0.488 Friction Coefficient (Soda Pendulum Test) — 0.1580.116 — — — — — Shell Four-Ball LNL — — 392 — — — — — EP Test LWL — —1236 — — — — — LWI — — 173 — — — — — Example Comparative Reference 9 1011 12 1 1 2 Composition Base Oil A (HG500) residue residue residueresidue residue 100 — (mass %) Base Oil B¹⁾ — — — — — — 100 Additive FMA — — — — — — — FM B — — — — — — — FM C — — — — — — — FM D — — — — — — —FM E 1 — — — — — — FM F — 1 — — — — — FM G 1 2 MoDTC — — — — 1 — — LFW-1Load (N)  44.5 0.08 0.084 0.065 0.061 0.067 0.097 0.101 Friction  88.90.122 0.117 0.089 0.085 0.097 0.126 0.123 Coefficient 133.3 0.137 0.130.103 0.101 0.113 0.142 0.137 177.8 0.142 0.136 0.108 0.105 0.116 0.1460.145 LFW-1 Wear Trace Width (mm) 0.4394 0.3315 0.442 0.485 0.37250.6205 — Friction Coefficient (Soda Pendulum Test) — — 0.086 0.086 0.1510.350 — Shell Four-Ball LNL — — 490 490 — 214 — EP Test LWL — — 15691569 — 1236 — LWI — — 240 260 — 146 — ¹⁾commercially-available oilcontaining antioxidant, antiwear agent and the like (general-purposeoil)

Example 13

98.7 mass % of the base oil A (HG500), 0.3 mass % of a phenolantioxidant and 1 mass % of FM A were mixed together, and a thermalstability test (based on JIS K2540) was conducted at 120 degrees C. for168 hours. No precipitate was observed at all.

As understandable from the above results, the lubricating oil additiveaccording to the aspect of the invention was considerably excellent infriction-coefficient reduction and wear resistance, even though theadditive contained no metal such as Mo or Zn, sulfur or phosphorus.Particularly notably, the friction reduction by the lubricating oiladditive according to the aspect of the invention was much moreexcellent than the friction reduction by MoDTC (Comparative 1), i.e., anadditive typically used so far for providing considerably excellentfriction reduction. As understandable also from Examples 4 and 5, whenadded to commercially-available general-purpose lubricating oil, thelubricating oil additive according to the aspect of the invention wasable to further reduce the friction coefficient. In addition, a smalladditive amount was sufficiently effective. Further, as understandablefrom Example 13, the lubricating oil additive according to the aspect ofthe invention was also excellent in heat resistance and oxidationresistance stability. Accordingly, the long-drain capabilities requiredfor the lubricating oil can be achieved, thereby contributing to wastereduction.

INDUSTRIAL APPLICABILITY

The lubricating oil additive and the lubricating oil compositioncontaining the same according to the aspects of the invention areapplicable to various lubricating oil.

1. A lubricating oil additive, comprising at least one lanolin alcoholderivative selected from the group consisting of a lanolin-alcoholsaturated fatty acid ester, a lanolin alcohol carbonate ester and alanolin alcohol ether.
 2. A lubricating oil additive, comprising atleast one steroid derivative selected from a steroid saturated fattyacid ester, a steroid carbonate ester and a steroid ether.
 3. Thelubricating oil additive according to claim 2, wherein the steroidderivative is a cholesterol derivative.
 4. A lubricating oilcomposition, comprising: lubricating base oil; and the lubricating oiladditive according to claim
 1. 5. The lubricating oil compositionaccording to claim 4, further comprising at least one additive selectedfrom the group consisting of viscosity index improvers, pour pointdepressants, antioxidants, ashless dispersants, friction modifiers,metal detergents, antiwear agents, rust inhibitors, metal deactivators,anti-emulsifiers and antifoaming agents.
 6. The lubricating oilcomposition according to claim 4, wherein the lubricating oilcomposition is used for engines, gears or industries.
 7. The lubricatingoil composition according to claim 5, wherein the lubricating oilcomposition is used for engines, gears or industries.
 8. A lubricatingoil composition, comprising: lubricating base oil; and the lubricatingoil additive according to claim
 2. 9. The lubricating oil compositionaccording to claim 8, further comprising at least one additive selectedfrom the group consisting of viscosity index improvers, pour pointdepressants, antioxidants, ashless dispersants, friction modifiers,metal detergents, antiwear agents, rust inhibitors, metal deactivators,anti-emulsifiers and antifoaming agents.
 10. The lubricating oilcomposition according claim 8, wherein the lubricating oil compositionis used for engines, gears or industries.
 11. The lubricating oilcomposition according claim 9, wherein the lubricating oil compositionis used for engines, gears or industries.